Linear Polarization Of Radiation Research Articles

Linear Polarization of Radiation in the 5876 Å (D3) and 5015 Å He I Lines in the Solar Atmosphere

Linear Polarization of Radiation in the 5876 Å (D3) and 5015 Å He I Lines in the Solar Atmosphere

Influence of Breit interaction on the linear polarization of radiation following electron impact excitation of B-like ions

SynopsisThe influences of Breit interaction on the total cross section and linear polarization of highly charged Ca15+, Xe49+, and W69+ ions in the electron impact excitation process are calculated by fully relativistic distorted-wave program REIE06. It is found that the influence of Breit interaction on the linear polarization is more obvious with the increase of atomic number Z.

On the Possibility of Determining the Magnitude of the Magnetic Field of Magnetars from the Emission Spectra of Hydrogen-Like Atoms

The widths of the spectral emission lines of a hydrogen-like atom in a superstrong magnetic field B >> (Zα)2 B 0, B 0 = m e 2 / e ≈ 4.41·1013 G, have been calculated. Specifically, the width of the α-line of the Lyman series is roughly 2 times smaller than in the absence of a magnetic field. Along with linear polarization of radiation, this makes it possible to determine the magnitude of the magnetic field of magnetars within the limits of the inequality B >> (Zα)2 B 0 from an analysis of the hydrogen emission spectrum. The general expression, so obtained, for the spectral width for an n → n′ transition with emission of a photon allows one in principle to calculate the width of any line of the emission spectrum of hydrogen in such a field with expansion of the possibilities of experimental identification of the latter.

Kinematic Identification of the Angular Power Distribution and the Linear Polarization of Radiation of an Arbitrarily Moving Charge

Methods of the classical theory of relativistic radiation are used to investigate general properties of the total angular power distribution of radiation of a charge and to analyze the corresponding components of linearly polarized radiation emitted by this charge.

Influence of Debye plasma on the cross section and linear polarization of x-ray radiation following inner-shell electron-impact excitation of highly charged Be-like Sc17+ ions

Detailed calculations using a fully relativistic distorted-wave method incorporating the Debye–Hückel potential are carried out for the electron-impact excitation cross sections from the ground state 1s22s2 (J = 0) to the individual magnetic sublevels of 1s2s22p and states of highly charged Be-like ions in the presence of a plasma environment. The effects of plasma screening on the cross section and linear polarization of the corresponding x-ray emission are investigated. For the line, it is found that the plasma screening has a pronounced effect and causes the cross section to decrease over the whole energy range considered. This dramatic influence also leads to a remarkable decrease in the linear polarization of subsequent x-ray radiation. However, for the line, the plasma screening effect on the cross sections is relatively larger than for the excitations, while its influence on the linear polarization of the radiation is very small.

On optical properties of nonspherical inhomogeneous particles

To solve the problem of light scattering by multilayer scatterers of an arbitrary axisymmetric shape, a separation of variables method that involves special scalar potentials and their expansions in spherical functions is developed. The approach is shown to yield highly exact results even for particles that have 100 layers or more. A graphic library that illustrates the optical properties of layered and homogeneous (with an effective refractive index) spheroids, spheres, and Chebyshev particles of various shapes and sizes (about 650 figures) is created and is put on the Internet. It is noted that the linear polarization of radiation transmitted forward through a polydisperse medium containing partially oriented nonspherical porous particles strongly depends on the structure of scatterers. It is shown that the difference between the degrees of polarization of layered and corresponding homogeneous scatterers can exceed 200–300%.

Linear polarization of radiation from ZnCdSe/ZnSe quantum wells induced by the anisotropic profile of interfaces

The low-temperature spectra of the exciton luminescence of the ZnCdSe/ZnSe quantum well grown in the [100] direction have been analyzed. It has been found that the observed radiation is linearly polarized in the well plane along either the [011] axis or the orthogonal $$[0\bar 11]$$ axis depending on the energy of exciting light. Polarization along the [011] axis is associated with the anisotropy of the geometric profiles of interfaces and corresponds to the polarization of excitons localized in the terraces elongated along the [011] axis, which are regions corresponding to an increase in the well thickness by a depth of one or several monolayers. The terraces appear due to the existence of growth steps on the interfaces. Anisotropy in the distribution of growth steps, i.e., a longer length of the steps along the [011] axis, is also responsible for the appearance of polarization along the $$[0\bar 11]$$ axis. Such a polarization appears due to the found specific channel of anisotropic exciton absorption. As a result of such absorption, free excitons with large wave vectors are excited. The excitation of excitons by light is indirect, because it involves additional processes of the elastic scattering of excitons on the interface growth steps. Prevailing scattering on an ensemble of longer growth steps (along the [011] axis) leads to the alignment of the wave vectors of excited excitons. A difference between the absorption probabilities for the polarizations of excitation along the [011] and $$[0\bar 11]$$ axes is caused by a difference between the probabilities of scattering on steps for excitons whose dipole moments and, correspondingly, the axes of the P-type wave functions for the holes involved in the process are oriented along and across the direction of the alignment of wave vectors of excitons.

Diagnostic of an ionized gas by recording linearly polarized radiation

The degree of linear polarization of radiation from an ionized gas is calculated analytically. The analytical results on the resonant transition in Al XII atoms agree (to within 4%) with the numerical results obtained from the ATOM code. The applicability of the analytic expressions derived to the analysis of the degree of linear polarization of radiation from this atomic transition and the related excitation cross section is discussed. The plots of the degree of linear polarization of radiation from an ionized gas as a function of the electron parameters are presented. The question of whether the spectropolarimetry can provide an independent optical diagnostic tool is discussed.

Weakly nonparaxial spatial solitons in a medium with Kerr nonlinearity

A version of perturbation theory is developed that intends to determine the field distribution of spatial solitons with a 2D transverse profile in a Kerr medium in the case of small deviations from paraxial conditions. An approximate master equation for transverse components of the electric field in the case of wide solitons is derived. By solving this equation starting from the unperturbed soliton, i.e., Townes mode with linear polarization of radiation, a solution with an axially symmetric field distribution is found. Dependences of the main soliton characteristics on the degree of paraxiality are determined.

Linear polarization of radiation from planar channeled electrons and positrons.

The polarization of channeling radiation emitted by planar channeled electrons and positrons has been calculated using the many-beam method. The radiation was found to be almost completely polarized in the direction perpendicular to the channeling plane for emission in the forward direction. This is an exact, analytical result and holds for all instances in which the particles satisfy the conditions for planar channeling.

Linear polarization of radiation from oblique and conical shocks

A simple model for synchrotron radio emission from oblique and conical shock waves is described, and the polarization properties are examined, assuming that the magnetic field in plasma upstream from the shock is random in direction. Such structures have been suggested as the origin of radio emission from the knots in radio jets that emerge from active nuclei, particularly on VLBI scales. It is found that conical shock waves in jets of circular cross section can yield polarized radiation with electric vector either parallel or perpendicular to the jet axis. The results provide insight into the extent to which conical shock waves might account for the polarization structures of jets in BL Lac objects and quasars that have been revealed by recent VLBI polarimetry. 13 refs.